Lubricating greases



Patented Dec. 18, 1951 LUBRICATING GREASES Herschel G. Smith, Wallingford, Troy L. Cantrell, Lansdowne, and Mark L. Hill, Boothwyn, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania.

N Drawing. Application September 12, 1949,

1 Serial No. 115,314

This invention relates tonovel lubricating greases and, more particularly, to soap-thickened mineral oils having a modified gel structure.

Dimculties have been encountered in the use of conventional mineral oil greases because of the fact that these conventional greases sometimes have indefinite and unstable gel structure. Slight variations in soaps or other basic ingredients produce changes in the gel structure which result in oil separation and limit the efficiency of the grease; its service life and the uses to which it can be applied.

It is therefore an object of this inventionto produce a soap-thickened grease which has a modified gel structure. 7

Another object of this invention is to manufacture a grease in which oil separation or bleeding does not take place.

A further object of this invention is to provide a grease which can be used on high pressure bearings.

These objects are accomplished in accordance with the present invention by the preparation of a grease which comprises a major amount of a mineral oil thickened to a grease with a soap and a minor amount, sufficient to prevent bleeding, of a metal phthalyl alkyl amide (a metalsalt of an N-alkyl phthalamidic acid) having the Q alert? "4 i' generic formula wherein M is a metal, a: is a whole number equal to the valence of M, and R is an alkyl group containing from 8 to carbon atoms.

In a soap-thickened mineral oil type'of grease, the soaps generally employed as thickeners include the sodium, calcium, aluminum and zinc or other metal salts of fatty materials derived from animal or vegetable fats or fatty acids. For example, the metal of the soap can be an alkali metal, an alkaline earth metal, and various other metals such as lead, chromium, tin, iron, cobalt, nickel, cadmium, mercury, etc., and

the fats or fatty acids can betallow, lard, cotton- 8 Claims. (01. 252- 333) a 2 facture. the addition of a metal phthalyl alkyl amide to any grease comprising a mineral oil thickened to the consistency of a grease with a soap. By

, the termfsoap-oil grease or soap-thickened grease we refer. to these commonly known greases.

vIn the preparation of the greases of .our invention the soap-oil greases are usually prepared first, and subsequently, from 0.1 to 5.0v

per cent by weight on the grease of the metal phthalyl alkyl amide is incorporated in the,

grease. However, the metal phthalyl alkyl amide may be added during the manufacture ofv ,the grease, for example, by being dissolved in the mineral oil used in compounding the grease.

The nature of our lubricating grease compo--, sition will be more clearly: understood .by ref.--

. erence to the following examples.

EXAMPLE I A grease having the following composition was prepared by the conventional pressure saponification method:

No.- 1 lard oil ..gal1ons '150 Water do 150 pale coastal oil (156 S. U. S. at

100 F.) allons 900- Powdered hydrated lime pounds 198 No. 1 inedible tallow do 100 The lubricant was then dehydrated and, during the stirring and cooling operation, 1 per .cent by weight of the calcium salt of amidic acid was added.

EXAMPLE? A cup grease having the following composition in parts by weight was prepared by the pressure saponification method:

During the stirring and cooling operation, 1 per cent by weight of the calcium salt of N-dodecylphthalamidic acid was incorporated there- EXAMPLE III A recoil mechanism grease having the following composition in parts by weight was prepare by'the pressure saponification method:

Two per cent by weight of the aluminum salt-- of N-dodecylphthalamidic acid was subsequently incorporated therein.

Our invention therefore contemplates c nthal EXAMPLE w A roller bearing grease was prepared having the following composition: I

Per cent by weight Sodium tallow soap 14 400 S. U. S. lubricating oil 7 at 100 F. 86

The above grease was treated with 1 per cent-"by weight of the sodium salt of N-hexadecylphthalamidic acid.

The viscosities expressed for the oils in the above examples are in Saybolt Universal seconds at 100 F. It is obvious that any of the soap-oil greases can be usedin accordance with our invention and that the above examples are merely illustrative. Variations will naturally occur to those skilled in the art.

The metalphthalyl alkyl amides which are incorporated in the soap-oil greasesin accordance with this invention are readily prepared, as will be shown, from metal hydroxides,- phthalic anhydride and primary alkyl amines; or, in the event the metal hydroxide of a particular metal is difficult to react, as, for example, the heavy metal hydroxides, the desired heavy metal N- alkyl phthalamidate' can be readily prepared by first preparing an alkali metal N-alkyl phthalamidate and reacting the latter with a water soluble salt of the desired heavy metal by a conventional double decomposition or metathesis reaction. We obtain particularly good results from the sodium, calcium andaluminum N-alkyl phthalamidates; however, satisfactory metal salts of N-alkyl phthalamides can be prepared from potassium, or other alkali metal, barium, strontium, magnesium, chromium, nickel, cobalt, Zinc, lead, tin, copper, cadmium, bismuth, etc.

The primary alkyl amines, which we employ in the preparation of the metal phthalyl alkyl amides are amines having the following generic formula:

wherein n is a number between 6 and 18. Some of the amines of this generic class are no-Fawn amine. Mono-lauryl amine Mono-myristyl amine Mono-palmityl amine Mono-stearyl amine and other primary alkyl amines having the above formula. Any of the aboveamines may be used with advantage in making our metal phthalyl alkyl amides. Furthermore, mixtures of such amines may be employed. For instance, one commercially available mixture of such amines is the so-called cocoamine prepared by converting the mixed acids of coconut oil into corresponding amines by well known methods. The

commercial cocoamine has an'average molecular weight of about 200-210 and contains a pounds so obtained, the new improvement agents being formed in situ in the oil.

The following examples illustrate various methods of preparing our metal phthalyl alkyl amides.

EXAMPLE A In this example, the improvement agent was prepared in situ in mineral oil from phthalic anhydride, dodecylamine and aluminum hydroxide, the agent so prepared having the following formula:

H OEJLFCHH camera The procedure employed in preparing this com-v pound was as follows:

Into an iron vessel equipped with means for heating, stirring and cooling, were charged 444 pounds of phthalic :anhydride to whichv 555 pounds of dodecyl amine wereslowly added. To this mixture were added 2000 pounds of a Texas oil having a viscosity of 70S. U. S. at F. and,

the components. were thoroughly agitated and slowly heatedto F.- After one'hour, 435 pounds of alumina (gelatinous 18 per cent Al(OH)3) were added and the mixture was kept at F. until the formation of water was com-,

pleted and no more water could be drawn off. From the kettle 2966 pounds of aluminum phthalyl dodecyl amide oil mixture were obtained.

The aluminum phthalyl dodecyl amide produced in situ in oil had .the following properties:

Gravity, API 20.8 Viscosity, SUV:

Neutralization No. a 1.11

ExAMPLEB A calcium phthalyl alkyl amide having the following formula:

wherein R is an octadecyl radical, was prepared substantially anhydrous oil solution of the cal'- 1 cium N-mono-octadecyl amido phthalate compounds so obtained was then cooled to room temperature.

The metalphthalyl alkyl amides which are deac'zsgeer scribed in the aboverexammes .havebeen; used as additives in mineral lubricating oils because of the-antirust and anticorrosion properties which they, confer "upon thelubricants in which they are incorporated. The-calcium and aluminum salts of phthalamidic acid are described in U. S. Letters Patent Nos.=2,3vs,442.and 2,378,443. It is truethat, as in the caseof mineral oil s, metal phthalyl alkyl amides also render grease compositions non-corrosive, to metal parts. Our invention, however, resides in'the discovery that entirely new and unexpectedresults are obtained byethe addition of metal phthalyl alkyl amides to soapeoil greases. j l a J'r-Q l xWe have discovered that themetal phthalyl alkyl. amides modify the ;gel structure" .of-the grease. Due to the fact that the grease has a different gel structure, the following properties of the grease are improved:

(1) The new gel structure does not break down as readily as the gel structure in the unmodified grease.

(2) A more plastic grease is produced.

(3) The texture of the grease is smoother and more uniform.

(4) The gel is notably stabilized against bleeding and oil evaporation.

Moreover, the grease does not become rancid over a long storage period because the metal phthalyl alkyl amide acts as a buffer to the soap solution.

The grease compositions of our invention have all been rigidly tested according to the methods prescribed in Army-Navy Aeronautical Specifications for Grease, AN-G-ba for lubricating performance, life, bleeding, evaporation, apparent viscosity, plasticity and low temperature torque. These tests clearly establish the fact that the gel structure of the original grease has been modified. The following comparative tests show the amount of bleeding and evaporation according to the Army-Navy standard specification tests.

Bleeding and evaporation test TEST AN-G-3a Per cent of separated oil due to bleed- Grease ing and evaporation after 50 hours (212 F.)

Grease prepared according to Example I and n lodified with 1% of calcium N-dodecyl phthalami ate Grease prepared according to Example I but not modified i. 24 Cup grease prepared according to Example II and modified with 1% of calcium N-dodecyl phthalamidate 0 Cup grease prepared according to Example II but not modified 28 Recoil mechanism grease prepared according to Example III and modified with 2% of aluminum Ndodecy1 phthalamidate 0, 1 Recoil mechanism grease prepared cc Example III but not modified l2 Roller bearing grease prepared according to Example IV and modified with 1.0% 01 sodium N-hexadecyl phthalamidate 0 Roller bearing grease prepared according to Example IV but not modified 5 The above tests clearly indicate the stability of our greases against bleeding or separation, particularly since our greases showed no signs of bleeding during the fifty-four hour test period. In fact, the unmodified greases showed some bleeding within 48 hours while the modified grease was still without separation after a two-week period.

The greases prepared according to our inventionwgive eminently, satisfactory lubrication, es; pecially when used on highgpressurebearings;at high surface temperatures. These greases are not consumed at an excessive rate while they are lubricating such hot bearings. In all cases the compositions give satisfactory lubrication in such applications as gun mechanisms, roller bearings and similar mechanisms.

Resort may be had to such modifications and variations as fall within the spirit of the invention and the scope of the appended claims.

We claim:

1. A lubricating grease which comprises a major amount of a soap-oil grease, and a minor amount, sufficient to prevent bleeding, of ame'tal phthalyl alkyl am'ide having the formula wherein R is an alkyl group containing from 8 to 20 carbon atoms, X is a whole number equal to the valence of M, and M is a metal.

2. A lubricating grease having a modified gel structure, comprising a major amount of a soapoil grease and a minor amount, from 0.1 to 5.0 per cent by weight of said soap-oil grease of a metal phthalyl alkyl amide having the formula t i I wherein R is an alkyl group containing from 8 to 20 carbon atoms, X is a whole number equal to the valence of M, and M is a metal.

3. A lubricating grease having a modified gel structure which comprises a major amount of a soap-oil grease and a minor amount, sufiicient to prevent bleeding, of a sodium phthalyl alkyl amide having the formula wherein R is an alkyl group containing from 8 to 20 carbon atoms.

4. The grease of claim 3 wherein R is a hexadecyl radical.

5. A lubricating grease having a modified gel structure which comprises a major amount of a soap-oil grease and a minor amount, sufiicient to prevent bleeding, of a calcium phthalyl alkyl amide having the formula ll 1% I l 15 wherein R is an alkyl group containing from 8 to 20 carbon atoms.

6. The grease of claim 5 wherein R is a dodecyl radical.

'7. A lubricating grease having a modified gel structure which comprises a major amount of a soap-oil grease and a minor amount, sufficient to prevent bleeding, 011m aluminum phthalyLaIkyl 8. The grease of claim 7 wherein R is a dodecyl amide having the formula radical.

HERSCHEL G. SMITH. TROY L. CANTRELL. 5 MARK L. HILL.

L 5 REFERENCES CITED 0 O The following references are of record in the file of this patent:

1 I I UNITED STATES PATENTS C-NH HNC Number Name Date L, g 2,370,442 Smith et a1 June 19, 1945 2,378,443 Smith et a1 June 19, 1945 g zgi gzsi fi gmup wntammg mm 8 15 2,408,102 Smith et a1 Sept. 24, 1946 2,403,103 Smith et a1 Sept. 24, 1946 

1. A LUBRICATING GREASE WHICH COMPRISES A MAJOR AMOUNT OF A SOAP-OIL GREASE, AND A MINOR AMOUNT, SUFFICIENT TO PREVENT BLEEDING, OF A METAL PHTHALYL ALKYL AMIDE HAVING THE FORMULA 